After downloading the mod from the link, unzip it on the your desktop or wherever. (it will be named DynamicCulturedMusic). Leave that alone for now.

Now launch EU4 and create a mod.

If you don't know how to do this: Click on 'Mods' it will be inbetween DLC and Settings. Then click on 'MOD TOOLS'. Click 'CREATE A MOD'. Name it whatever, for the Version put 1.29, and for the Directory put whatever (example: mod/StalinIsDummyThicc). Click 'CREATE MOD', and you'll be graced with a window letting you know that the mod has been created. Click 'OK', then exit out of the next window that pops up.

Now go to: Documents/Paradox Interactive/Europa Universalis IV/mod

You should see a lot of .RAR or .ZIP folders and .MOD files, depending on how many mods you've installed (Ignore these). Your looking for the mod you just created and that should be at the top as a basic File Folder, it will have the same name as what you put for the
Directory (ie. StalinIsDummyThicc).

Go into it (with consensual permission of course) inside will be a file names descriptor (ignore it, it's just capitalist propaganda). Now go and find the folder 'DynamicCulturedMusic' and drag and drop or copy and paste the contents of that folder into the file you where just in. It will ask you to replace the descriptor file, click 'YES DADDY!' (if you don't have 'YES DADDY!" as an option, uninstall life)

Everything should be good to go, exit out of the EU4 launcher and launch it back up.

Enable the mod and enjoy!

If you don't know how to enable mods: Click on 'Mods' and then click on 'MANAGE MODS', the one you just created should be at the very bottom of the 'Mods' list, with the name you put when you created it, Enable it, click 'DONE' and play the game. Enjoy!

If it's not working, then perhaps try disabling the DLCs that introduce music, some guy in the comments suggested it. If not then I'm not sure.